Apparatus for triggering a dropout fuse comprising a rotatably mounted trip arm which engages an operator in the fuse



May 18, 1965 w. A. eussow 3,184,567

APPARATUS FOR TRIGGERING A DROPOUT FUSE COMPRISING A ROTAIABLY MOUNTEDTRIP ARM waxcn ENGAGES AN OPERATOR IN THE FUSE 8 Sheets-Sheet 1 FiledJuly 25, 1962 mok muao 025mm May 18, 1965 w. A. GUSSOW 3,184,557

APPARATUS FOR TRIGGERING A DROPOUT E MPRISING A ROTATABLY MOUNTED TRIPAR 11 ENGAGES AN OPERATOR IN THE FUSE Filed July 25, 1962 s Sheets-Sheet2 29 6 M 13 19 w 0 3k 81/ 111' w JM 33 i 31 are H May 18, 1965 w. A.GUSSOW 3,184,567

APPARATUS FOR TRIGGERING A DROPOUT FUSE COMPRISING A ROTATABLY MOUNTEDTRIP ARM WHICH ENGAGES AN OPERATOR IN THE FUSE Filed July 25, 1962 8Sheets-Sheet 3 .153 3A. 7 m E Z5/.3-B.

W. A. GUSSOW May 18, 1965 APPARATUS FOR TRIGGERING- A DROPOUT FUSECOMPRISING A ROTATABLY MOUNTED TRIP ARM WHICH ENGAGES AN OPERATOR IN THEFUSE 8 Sheets-Sheet 4 Filed July 25, 1962 N\N I m mw 4 VWW/WWWA QMQXQQNQW May 18, 1965 w. A. GUSSOW 3,184,567

APPARATUS FOR TRIGGERING A DROPOUT FUSE COMPRISING A ROTATABLY MOUNTEDTRIP ARM WHICH ENGAGES AN OPERATOR IN THE FUSE Filed July 25, 1962 8Sheets-Sheet 5 May 18, 1965 w. A. GUSSOW 3,184,567

APPARATUS FOR TRIGGERING A DROPOUT FUSE COMPRISING A ROTATABLY MOUNTEDTRIP ARM WHICH ENGAGES AN OPERATOR IN THE FUSE Filed July 25, 1962 8Sheets-Sheet 6 z 3 w\ \\\\\\/A\\\ g i|..//////////// n W M M 0 U m 11 1. III! 8 w w 1 4 /////v////v/ M Y\\\\ z N m 8 +4 6 i May 18, 1965 w.A. GUSSOW 3,184,567

APPARATUS FOR TRIGGERING A DROPOUT FUSE COMPRISING A ROTATABLY MOUNTEDTRIP ARM WHICH ENGAGES AN OPERATOR IN THE FUSE 8 Sheets-Sheet 7 FiledJuly 25, 1962 W. A. GUSSOW May 18, 1965 3,184,567

G A DROPOUT FUSE COMPRISI A ROTATABLY MOUNTED TRIP ARM WHICH APPARATUSFOR TRIGGERIN ENGAGES AN OPERATOR IN THE FUSE 8 Sheets-Sheet 8 FiledJuly 25, 1962 APPARATUS FOR TRIGGERENG A DRQPOUT COMPRISING A ROTATABLYMQEUNTED Till? Rsltgll WHICH ENGAGE AN QPERATOR IN THE William A.Gussow, fit. Petershurg, Fla, assiguor to S dz C Electric Company,Chicago, Ill., a corporation of Delaware Filed July 25, 1962, Ser. No.212,236 9 Claims. (Cl. Ziltl114) This invention relates, generally, toapparatus for causing the operation of circuit interrupters, such asdropout fuses, by means other than the blowing of their fusible elementsand it has particular relation to the triggered fuse constructiondisclosed and claimed in the copending application of Sigurd I. Lindell,Serial No. 210,093, filed July 16, 1962, and assigned to the assignee ofthis application. The dropout fuse construction with which thisinvention can be used is shown in US. Patent No. 2,599,186, issued June3, 1952, to S. I. Lindell.

As disclosed in the application above referred to it is sometimesdesirable to cause a fuse of the kind shown in the above patent tointerrupt the current flow and then to dropout and isolate the circuitin which it is connected in response to the operation of means otherthan the blowing of its fusible element. It is well understood that thefusible element has a certain time-current characteristic and it maybecome necessary to isolate the circuit under circumstances where thefusible element would not be responsive from either a time or a currentstandpoint. The speed of response may be too low or the current requiredmay be too high. An example is found where the circuit is to be openedin which the fault current flow may be of insufficient magnitudeinitially to cause the fusible element to blow, or to blow within ashort enough interval, to obtain the required circuit isolation. Such asituation may exist when one or more turns of the windings of atransformer protected by the fuse become short circuited and the faultmust progress to a great extent before the current rises to a magnitudesufficient to blow the fuse. The fault current flow often can bedetected only by a differential protective arrangement in which adifferential relay is responsive to the fault and can be employed totrigger the fuse of this invention. This causes it to interrupt thecurrent flow and isolate the circuit without blowing the fusibleelement. The above Lindell application discloses and claims preferredembodiments of triggered fuse constructions, one of which is shownherein, and also it discloses means external to the triggered fuseconstructions for triggering them to which means the claims of theinstant application are directed.

Among the objects of this invention are: To provide for externallytriggering a circuit interrupter such as a dropout fuse withoutinterfering with its dropping out once it has been unlatched from itsnormal operating position; to move a rod-like actuator or operatorendwise of a dropout fuse for releasing a spring driven arcing rod forcircuit interruption and for unlatching the fuse at its upper end froman upper line terminal by applying a force endwise of the fuse tubethrough it lower end as the result of rotation of a trip arm mounted ona bracket extending from the lower line terminal on which the fuse ispivotally mounted; to position the trip arm normally out of the path ofthe are products flowing from the dis charge end of the fuse so thatwhen the fusible element blows and a heavy exhaust occurs on a severefault there is no interference with the flow of the arc products due tothe trip arm; to position the trip arm so that it does not interferewith the manual hook stick operation of the fuse as a disconnectingswitch or the insertion on or removal from the fuse mounting of the fuseby a live Patented May 18, 1965 ICE line stick; to protect the trip armfrom sleet without interfering with the normal dropout action of thefuse; to provide a trip free operating connection to the trip arm; tolimit the swinging movement of the trip arm in either direction; torotate the trip arm by an actuating lever insulatingly mounted about anaxis parallel to the axis of rotation of the trip arm; to mount theactuating lever on a rotatable insulator extending parallel to andadjacent to the insulator that supports the lower line terminal; tooperate simultaneously by external means a plurality of dropout fuses ina new and improved manner; and to release the energy stored in a springoperator to impact the operator of a triggered dropout fuse foreffecting its operation with a snap action.

in the drawings:

FIG. 1 is a view showing a typical installation of triggered fuseconstructions in accordance with this invention, the view showing thevertically extending supports with the insulator bases mounted thereon,one of the assemblies showing the construction at the lower end of thedropout fuse, and showing external trigger operating mechanism for oneof the units together with means for commonly operating them to triggerall of the dropout fuse constructions.

FIG. 2 is a view, in side elevation, of the construction shown in FIG. 1with the dropout fuse embodying the present invention mounted onlaterally extending insulators from a support.

FIGS. S-A, 3-3, 3-C and 3E (FIGS. 3-C and 3-E being at an enlargedscale) placed end to end in the order named show certain details ofconstruction in vertical longitudinal section in a dropout fuseembodying the present invention; FIG. 3-C showing the fusible elementterminal latch means in the latched position and FIG. 3-D correspondingto FIG. 3-C but showing the fusible element terminal latch means in theunlatched position with the fusible element terminal released and movingupwardly to interrupt the circuits accompanied by release of the fusetube latch release means to permit the dropout fuse to swing downwardlyto the open position.

FIG. 4 is a horizontal sectional view, at a reduced scale, takengenerally along the line 4-4 of FIG. 3-E.

FlG. 5 is a horizontal sectional view, at a reduced scale, takengenerally along the line 55 of FIG. 3-C.

FIG. 6 is a horizontal sectional view, at a reduced scale, takengenerally along the line 6-6 of FIG. 3C.

PEG. 7 is a view, at an enlarged scale, of the external triggeroperating mechanism that is mounted at the lower end of each of thedropout fuses, the mechanism being shown in the non-operated positionand the sleet hood being shown in section in order to illustrate moreclearly certain of the parts of the mechanism.

FIG. 8 is a sectional view taken generally along the line 38 of FIG. 7.

FIG. 9 is a view, similar to FIG. 7, but showing the trip arm impactingthe lower end of the operator to trigger the fuse release mechanism withthe actuating lever being shown in the fully operated position to whichit is moved for actuating the trip arm.

Referring now particularly to FIGS. 1 and 2 of the drawings, it will beobserved that the reference character it} designates, generally, adropout fuse construction which is intended for polyphase operation. Forexample, the dropout fuse construction 10 can be employed forcontrolling the connection of a three phase circuit to a suitablealternating current power supply circuit. While the dropout fuseconstruction ltl can be employed in circuits operating at variousvoltages, it is intended particularly for operation in connection withcircuits operating at voltages of the order of 34.5 kv. and abovedepending upon the requirements of the system. It will be underanswerstood that three dropout fuse constructions 1d are employed for a threephase system and, since they are of identical construction, adescription of one will suffice for a description of all of them.

Each dropout fuse construction It) includes a support 11 in the form ofa channel base that is arranged to be supported suitably (by means notshown) so as to extend generally vertically. The support 11 carriesupper and lower insulators 12 and 13 in laterally extending relation. Atthe distal ends of the insulators 12 and 13 upper and lower lineterminals 14 and 15, respectively, are mounted. They are interconnectedby a dropout fuse that is indicated, generally, at 16. The details ofconstruction of the dropout fuse 16 are generally similar to theconstruction shown in the patent above referred to. According-1y, only ageneral description thereof will be set forth herein.

The dropout fuse 16 includes a fuse tube 17 of suitable insulatingmaterial which carries an upper fuse tube terminal, shown generally at18, in contact engagement with the upper line terminal 14. The fuse tube17 also has a lower fuse tube terminal, shown generally at 19, which issuitably connected to and mounted on the lower line terminal 15. A latcharm 2.11 on the upper line terminal 14 serves to latch the upper fusetube terminal 18 in contact engagement therewith. The lower fuse tubeterminal 19 is pivoted, as indicated at 21, on the lower line terminal15. For a complete understanding of the manner in which the upper fusetube terminal 18 is latched to the upper line terminal 14 and the lowerfuse tube terminal 19 is pivoted to the lower line terminal referencecan be had to US. Patent No. 2,578,255, issued December 11, 1951, to S.I. Lindell. However, it will be understood that other latching and pivotmeans can be employed as may be desired.

In order to move the latch arm 21) to the unlatching position, a flange24 is provided on the lower end of a slidable unlatching tube 25. As setforth in the patents above referred to, provision is made on blowing ofa fusible element for moving the unlatching tube 25 uptwardly to liftthe latch arm for the purpose of unlatching the upper fuse tube terminal18 from the upper line terminal 14 and permitting the dropout fuse 16 topivot at 21 on the lower line terminal 15 to an open position. Theunlatching tube can be moved upwardly manually by causing an arm 26 on apull ring 27 to lift the same. The pull ring 27 is pivoted at 28 on theupper fuse tube terminal 18 and the arrangement is such that, when theprong of a live line stick is inserted in the pull ring 27 andsufficient force is applied thereto, the pull ring 27 is rotated aboutits pivot 28 to cause the arm 26 to engage the underside of the flange27 and move the unlatching tube 25 upwardly and at the same timeswinging the latch arm 20 to the unlatched position.

The lower fuse tube terminal 19 has an eye member 29 mounted thereon forreceiving a prong of a live line stick to permit application of thedropout fuse to the lower line terminal 15 in conventional manner.Thereafter, the prong of the live line stick is inserted in the pullring 27 and the dropout fuse 16 is swung to the position shown in FIG. 2where the upper fuse tube terminal '18 is in contact engagement with theupper line terminal 14 and is latched in this position by the latch arm20. A resilient bumper 31) is carried by the lower line terminal 15 forcushioning the downward swinging movement of the dropout fuse 16 afterit has been released by operation of the latch arm 20 in the mannerdescribed.

As pointed out above, it is desirable to trigger the operation of thedropout fuse 16 under certain circumstances =when its fusible element isnot required to blow and yet it is desired to take advantage of thecircuit interrupting capabilities of the dropout fuse 1% for opening thecircuit. For this purpose an external trigger operating mechanism, showngenerally at 33 in FIGS. 1 and 2, is provided.

A part of the external trigger operating mechanism 33 is mounted on asupport bracket 34 in the form of a plate which is mounted on the distalend of the lower insulator 13 of each fuse construction it? between itand the respective lower line terminal 15. Extending outwardly from thesupport bracket 34 is a sleet hood 35 which overlies a major portion ofthe external trigger operating mechanism 33 and is spaced, as indicatedat as in FIG. 1, from the juxa posed side of the lower line terminal 15a suiiicient distance so that ice does not form therebetween. Thetrigger operating mechanism 33 includes a rotatably mounted trip arm 37,a portion of which extends below the sleet hood 35 in the non-operatedposition and the details of construction of which are shown in FIGS. 7,8 and 9 and described hereinafter. For operating the trip arm 37 anactuating lever 38 is provided. it is mounted for rotation with thedistal end of a rotatable insulator 39 which extends generally parallelto and below the lower insulator 13 and is mounted in a bearing 40 thatis carried by an extension plate 41 on the lower end of the support 11.An operating arm 12 extends radially from the base of the rotatableinsulator 39 for rotating it between stop pins d3-43 which extendforwardly from the extension plate 41 and into the path of movement ofthe operating arm 42.

When a polyphase dropout fuse construction is en ployed, for example athree phase installation, three dropout fuses 16 are used and provisionis made for effecting their simultaneous operation in order to dropoutand clear all three phases at the same For this purpose each of theoperating arms 4-2 is pivotally connected at to an interphase rod 15 andprovision is made for longitudinally moving it to rotate simultaneouslythe three rotatable insulators 39 for operating the three externaltrigger operating mechanisms 33. Any suitable means can be employed formoving the interphase rod 45 endwise. Preferably provision is made formoving it with a snap action. For example, it can be connected pivotallyat 16 to one arm of a bell crank 47 which is pivoted at 48 on a suitablesupport 49 in the form of a channel base. The other arm of the bellcrank 47 is pivotally connected at 56 to a pull rod 51 that is connectedat its lower end pivotally at 52 to an arm 53 of a spring operator thatis indicated, generally, at 54. A handle permits manual cocking of anoperating spring in the spring operator 54. The spring in the springoperator 54 can be triggered by any suitable means, such as bydifferential relay means or by a system such as disclosed in applicationSerial No. 172,017, now Patent No. 3,116,391, filed February 8, 1962, byS. I. Lindell and L. V. Chabala. Such current responsive means effects arelease of the cocked spring to rotate the arm 53 with a snap action andeffect a corresponding accelerated movement of the interphase rod 415which is accompanied by a corresponding high speed rotation of theseveral rotatable insulators 39 and corresponding movement of theactuating levers 33 carried thereby. On return movement of the handle 55the interphase rod 45' is returned to the position shown in FIG. 1 ofthe drawings. As will appear hereinafter, a trip free connection isprovided between each actuating levers 3S and the trip arm 37 operatedthereby. Accordingly, after each actuating lever 38 has caused therespective trip arm 37 to trigger the dropout fuse 16 associatedtherewith, the construction is such that the trip arm 37 is promptlyretrieved to its non-operated position and out of the path of thedropout fuse 16 so that it can fall freely to the open position.

Reference now will be had to FIGS. 3-A, 3-13, 3C and 3E of the drawings.It will be recalled that these figures should be placed one above theother in the order named in order to provide a complete longitudinalsectional view of the details of construction of the dropout fuse 16.Also, it will be understood that FIGS. 3-C and 3-E are shown at a largerscale than FIGS. 3-A and 3-B in order to show more clearly the detailsof construction of the fusible element terminal laatch means forming apart of the trigger means that is operated by the external triggeroperating mechanism 33 to release the dropout fuse 16 from its latchedconnection to the upper line terminal 14 and permit it to fall to theopen position. Here it will be observed that the fuse tube 17, which maybe formed of a phenolic condensation product, is provided with aninsulating liner 57 that may be formed of high strength material such asfiber. Within the liner 57 is a stack of cakes 58 or boric acid orsimilar arc extinguishing material which are held in place by a layer 59of cement. The cakes 58 are apertured to provide a longitudinallyextending bore 6h therethrough. Extending and endwise movable throughthe bore 60 in the cakes 58 of arc extinguishing material is a rod-liketerminal 61 which is provided at its upper end with a cylindricalcontact 62 that is engaged by contact fingers 63 under substantialpressure exerted by a garter spring 64. The contact fingers 63 aresecured to a contact fitting 65 to which electrical connection is madeby a connector tube 66 which extends upwardly along the inner surface ofthe fuse tube 1'7 and is connected at its upper end to the upper fusetube terminal 18. This arrangement provides a direct connection betweenthe upper fuse tube terminal 18 and the rod-like terminal 61 throughwhich the current normall flows.

In order to withdraw the rod-like terminal till through the bore 69 andextinguish the arc therein, the rod-like terminal 61 is provided with anextension rod 67 which is connected to the contact 62 at its lower endwhile its upper end is connected to a cable connector assembly 63 thatis fiexible in nature and is trained over a pulley 69. The other end ofthe cable connector assembly 6% is connected to a strap 7%} which isconnected at 71 to the contact fitting 65. This arrangement provides aconnection between the rod-like terminal 61 and the contact fitting 65after the contact 62 is moved out of engagement with the contact fingers63. The pulley 69 is carried by a clevis '72 which depends from a yoke'73 that is carried by a tube end fitting '74 that is located at theupper end of the compression tube 75 which is slidable within theconnector tube 65 and which has an annular fitting '76 at its lower endagainst which the coil compression spring 7'7 reacts. The lower end ofthe coil compression spring 77 reacts against the upper side of thecontact fitting 65 and it serves to bias the compression tube '75upwardly. it will be understood that the compression tube '75 and partsmovable therewith constitute fuse tube latch release means, indicatedgenerally at 73, with the arrangement being such that, when the rod-liketerminal 61 is released, the coil compression spring 77 moves thecompression tube 75 upwardly carrying with it the pulley 69. As a resultthe rod-like terminal 61 moves upwardly at a speed which is twice thatof the speed of upward movement of the compression tube 75. Thecompression tube '75 is telescoped within the unlatching tube 25 and atthe end of its upward movement the tube end fitting 74 engages the upperend 25' of the unlatching tube 25. It will be recalled that thismovement is accompanied by upward movement of the flange 24 which liftsthe latch arm 20 and unlatches the upper fuse tube terminal 18 from theupper line terminal 14 and permits the dropout fuse 16 to rotate aboutthe pivot 21 to the open position.

Referring now particularly to PEG. 3-C it will be observed that ametallic annular fitting 80 is threaded into the lower end of the liner5'7. Secured to the lower end of the fitting 8% is a metallic exhausttube 81 which extends downwardly over the inner surface of the fuse tube17 where it is joined through a spacing ring 82, FIG. 3E, to the innersurface of the lower fuse tube terminal 19 which is generallycylindrical in configuration and which extends over the outer surface ofthe lower end of the fuse tube 17 and projects downwardly therebelow. Itwill be understood that trunnions are provided on the lower fuse tubeterminal 19 by means of a suitable fitting as described in more detailin US. Patent No. 2.578,255, issued December 11, 1951, to S. I. Lindell.

Referring again to FIG. 3-C, it will be observed that the lower end ofthe rod-like terminal 61 has connected thereto one end of a fusibleelement that is indicated, generally, at $3 and which serves to restrainupward move ment of the rod-like terminal 61 under the influence of thecoil compression spring 77. The fusible element 83 is connected at itslower end to a fusible element terminal that is indicated, generally, at84 and provision is made for restraining it and for releasing it thatwill be described presently. The fusible element 83 may include a fusewire 85 in the form of a helical coil of silver wire surrounding astrain wire 86 of high strength metal such as a nickel chromium alloy.It will be understood that it is conventional to connect a fusibleelement terminal, similar to the fusible element terminal 84, to themetallic annular fitting 80 or to the upper end of the metallic exhausttube 31. When such a construction is employed and the rod-like terminal61 is to be released for operating the dropout fuse 16, it is necessarythat the fusible element 83 blow. When this takes place, the rod-liketerminal 61 moves upwardly through the bore of) in the cakes 58 of solidarc extinguishing material and the arc incident to the blowing of thefusible element 33 is drawn between the lower end of the rod-liketerminal 61 and the upper end of the fusible element terminal $4 or somepart of the metallic annular fitting St) or of the metallic exhaust tube81 and, because of the intensity of the blast action and theaccompanying pressure, it is desirable that the flow of these areproducts be substantially unimpeded in their escape downwardly throughthe metallic exhaust tube 81 to the atmosphere. However, such operationcan be effected only by blowing of the fusible element 33 and thisordinarily takes place only when the current flow therethrough is ofpredetermined magnitude exceeding its normal load current carryingcapacity.

As indicated hereinbefore it is sometimes desirable to release therod-like terminal 61 for movement upwardly through the bore 60 in orderto take advantage of its arc extinguishing capability under conditionswhere the fusible element 83 of the dropout fuse 16 would not respond orblow or would not respond or blow with the desired speed. Accordingly,trigger means, shown generally at 89, are provided for releasing thefusible element terminal 84 in response to operation of the externaltrigger operating mechanism 33. As a result the rod-like terminal 61moves upwardly and carries with it the fusible element 83 and thefusible element terminal $4. This action would normally be made to takeplace only when load current or fault current of low value, as instepdown substation transformer installations under overload conditions,secondary fault conditions or internal fault conditions, is flowingthrough the dropout fuse 16. Internal faults may occur when thetransformers are carrying little or no load. Under such conditions thecurrent to be interrupted may be only slightly higher than normalexciting current. Such relatively low currents can be readilyinterrupted and the arc drawn between the terminal 84- and the triggermeans 89 or the fitting 80 extinguished since the bore 60 in the arcextinguishing material 58 has suitable diameter and adequate length toeffect these results. While there is a reduction in break distance dueto the withdrawal of the complete fusible element 83 and the terminal84, the length of the bore 60 is made sufficient to accommodate thisextension of the rod-like terminal 61.

For cooperating with the trigger means 89 the fusible element terminal83 is provided with an annular shoulder portion 9i) which has an annularlatch surface 91 at its upper end that is arranged to be engaged byfusible element terminal latch means, shown generally at 92. The fusibleelement terminal latch means 92 is provided not only for making amechanical connection between the fusible element terminal 84 and thelower fuse tube terminal 19 to restrain the coil compression spring 77but also it is arranged to provide a high pressure electrical connectiontherebetween. in general, instead of directly interconnecting thefusible element terminal 84 to the upper end of the metallic exhausttube 81 to provide the desired releasable mechanical and electricalconnections thereto, the fusible element terminal latch means 92 at theupper end of the metallic exhaust tube 81 provides these releasableconnections. As will appear hereinafter the latch means 92 extends tothe lower end of the metallic exhaust tube 81 where the mechanical andelectrical connections are completed to it and to the lower fuse tubeterminal 19. I11 addition the construction of the fusible elementterminal latch means 92 and parts associated therewith is such that aminimum of obstruction is offered to the flow of the are productsthrough the metallic exhaust tube 31. It will be recalled that this isparticularly important when the fusible element 83 blows as a result ofthe flow therethrough of high fault current which results in theevolution of a substantial quantity of arc extinguishing material fromthe bore and the generation of substantial pressure within the metallicexhaust tube 81 which should be promptly released to the atmosphere.

It will be observed that the fusible element terminal latch means 92includes a pair of latch hooks 93-93 that are laterally movable and areformed of good conducting material such as copper. The latch hooks 93-93are provided with jaw portions 94-9 3 the undersurfaces 942-94 of whichare arranged to engage the annular latch surface 91 and restrain upwardmovement of the fusible element terminal 84. The jaw portions 94-94 areprovided with facing cylindrical surfaces 95-95,

FIG. 6, which may be V-shaped and are arranged to engage opposite sidesof a shank 96 that forms an integral part of the fusible elementterminal 84 and from which the annular shoulder portion 9% depends.Also, the jaw portions 94-94 have outflared surfaces 97-97 for guid inga beveled lower end 93 of the annular shoulder portion 90 between thejaw portions 94-94, which are spaced apart as described hereinafter,when the fusible element terminal 84 is drawn downwardly through thefuse tube 17 to tension the spring 77 and to place the fusible elementterminal 84 in engagement with the fusible element terminal latch means92.

To facilitate this latching operation the annular shoulder portion 90 isinternally threaded, as indicated at 99, for removably receiving a tool10% which is shown by broken lines in FIG. 3C. tool 1% is in the form ofan elongated rod which is threaded at one end for engagement with thethreaded opening 99 in the annular shoulder portion 90 of the fusibleelement terminal 84. The tool 100 is long enough to extend out of thelower end of the fuse tube 17 and out of the lower end of the lower fusetube terminal 19 while it is in engagement with the threaded opening 99of the annular shoulder portion 9t) and the fusible element terminal 84is retracted to a position within the bore as. An application of endwisetension to the tool 199, the fusible element terminal 84 is drawndownwardly through the bore 60 and the spring '77 is compressed to storethe energy for moving the rod-like terminal 61 upwardly when it isreleased. After the fusible element terminal $4 has been latched by thefusible element terminal latch means 92, the tool ltltl is unscrewed andwithdrawn.

As shown in FIGS. 3-C and 5 the latch hooks 93-93 are provided with flatshanks 102-192 which are secured by transversely extending rivets1%3-103 to the bifurcated ends 194-104 of flexible beam members 105-165which may be formed of good conducting material such as spring temperberyllium copper. The lower ends of the flexible beam members 195-195are secured by press fit and by rivets res-see to a lower bridge 197,FIGS. 3-13 and 4, which is formed of good conducting material,

It will be understood that the rease? such as brass, and which extendsinto contact engagement with and is suitably secured by brazing or byscrews to th lower end of the metallic exhaust tube 81 and to thespacing ring ('52 and in contact engagement with the inner surface ofthe lower fuse tube terminal 19. In order to increase the flexibility ofthe beam members 165-105 they may be provided with reduced diameter orflattened intermediate portions as indicated at 193-108. Now it will beapparent that the fusible element terminal 84 is electrically andmechanically connected to the lower fuse tube terminal 19 through thelatch hooks 93-93 carried by the flexible beam members 1395-105 whichare supported on the lower bridge 107 that is mechanically andelectrically connected to the lower fuse tube terminal 19 and partsimmediately associated therewith.

With a view to holding the jaw portions 94-94 of the latch hooks 93-93in high pressure latching engagement with the fusible element terminal84 and to insure that the engagement here is positive and will beunaffected by vibration, lower wedging surfaces 111-111 face outer sides112-112 of slotted openings 113-113, FIG. 5, in a cam member 114, whichmay be formed of brass, and which is secured at 115 to the upper end ofan operator 116 that is in the form of a metallic tube having a centralopening 117 extending through it for receiving the tool liltl previouslyreferred to. As shown in FIG. 3-E, the lower end of the operator 116 isslidably mounted in a central opening 118 in the lower bridge 107. Acoil compression spring 119 reacts between the underside of the lowerbridge 107 and a shouldered fitting 129 on the lower end of the operator116 to bias the latter downwardly. This maintains the lower portions ofthe outer sides 112-112 of the slotted openings 113-113 in the cammember 11 in wedging engagement with the lower portions of the wedgingsurfaces 111-111 and springs the beam members 105-195 toward each other.As a result the jaw portions 94-94 are firmly held in resilient pressureengagement with opposite sides of the shank 96 of the fusible elementterminal 84 and the undersurfaces 94-94 thereof are held in latchingengagement with the annular latch surface 91 on the annular shoulderportion 90.

When the fusible element terminal is to be latched or to be released, itis desirable that the jaw portions 94-94 be moved laterally apartsimultaneously and completely out of engagement with the annular latchsurface 94 to the end that there is no likelihood on release that itwill be hung up on one of the jaw portions 94. In part, this isaccomplished through the provision of upper wedging surfaces 123-123,FIG. 3-C, on the inner sides of the shanks 102-102; of the latch hooks93-93. When the operator 116 is moved upwardly to permit latching of theterminal 34 or to release it, the operator 116 carries with it the cammember 114. The inner sides 124-124 of the slotted openings 113-113engage with the upper wedging surfaces 123-123 and move the jaw portions94-94- apart to permit entry of the shoulder portion 90 as drawn down bythe tool 199 or its release as the case may be. This is permittedbecause the outer sides 112-112 of the slotted openings 113-113 moveupwardly with respect to the lower wedging surfaces 111-111. Additionaltime for release of the terminal 84 from the latch hooks 93-93 can beobtained by causing the inner sides 124-124 of the openings 113-113 inthe cam member 114 to engage wedgingly flat sides 126-126 of the shanks192-192. Such action is obtainable by providing for a correspondingendwise inward movement of the operator 116 and the jaw portions 94-94are held apart.

It is desirable that the annular shoulder portion 90 of the terminal 84be centered and that the jaw portions 94-94 be guided to move in a planeto the end that they engage or disengage the contact shank 96 and theannular latch surface 91 of the annular shoulder portion ans ass? 9%when the fusible element 3 is to be engaged or released when theoperator lid is moved endwise to actuate the latch hooks 9393. This ispartly accomplished by guiding the jaw portions 9494- in their lateralmove ment together or apart between upper bridge members l27ll27, FIGS.3-C and 6, which are secured at their ends to the lower end of themetallic annular fitting 8t) as by brazing. Intermediate the ends of theupper bridge members 1273l27 transverse grooves l28128 are formed forreceiving and guiding the annular shoulder portion 9%. Because ofcorrosion or for other reasons after the dropout fuse 16 has been inservice a long period, there may be the tendency for the annular latchsurface 911 to become attached to the undersurfaces 9d-9d' of the jawportions 9d94. When the jaw portions 94-9d are moved apart, unless theycompletely disengage the opposite sides of the annular latch surface 91,it might be possible that the annular shoulder portion 9d would hang upon one of the jaw portions 94. This is prevented since the transversegrooves l2-S12ti in the upper bridge members 127-l27 hold the annularshoulder portion 90 in centered relation with respect to the oppositelymoving jaw portions 94-94. Since their movement apart is insured by theengagement of the upper wedgiug surfaces l23-123 with the inner sides Ei-41% of the slotted openings 113-413, the fusible element terminal 84always is positively released as a result of the upward movement of theoperator M6.

Referring now particularly to FIG. 3-D, it will be observed that thisshows the construction illustrated in FIG. 3-C but with the operator lidand cam member 14 thereon moved upwardly to disengage the lower wedgingsurfaces ill-Alli and engage the upper wedging surfaces l23l23 to movethe jaw portions 9d-94 apart and out of engagement with the annularlatch surface 931. As a result the fusible element terminal 9d isreleased to move upwardly, as indicated by the arrow 129, under theinfluence of the coil compression spring 7'7. the releasing movement ofthe fusible element terminal 84, the annular shoulder portion 9ththereof is centered by the transverse grooves, one being shown at 123 inFIG. 3-D, while the jaw portions 94-94 are moved apart in one plane asguided by the upper bridge members 127-127. As a result of the releaseof the fusible element terminal 84, in the manner described, it movesupwardly under the influence of the coil compression spring 77 in thedirection indicated by the arrow 129, FIG. 3D, and, if current isflowing in the circuit in which the dropout fuse T6 is connected, an arcis drawn between the lower end of the annular shoulder portion 9% andone or the other or both of the jaw portions M-9d. The are is extendedinto the bore 6% and extinguished as the rodlil'e terminal movesupwardly therethrough together with the fusible element $3 and fusibleelement terminal 84.

As a further result of the release of the fusible element terminal Sidby separation of the jaw portions 9'49l, the coil compression spring 77moves the compression tube 7:? upwardly sufficiently far to cause thetube end fitting 7 to engage the underside of the upper end 25 of theunlatching tube 25. he unlatching tube 25 moves upwardly carrying withit the flange to lift the latch arm 2d and permit the dropout fuse T6 torotate about the pivot 21 on the lower line terminal 15 downwardly toopen position where it engages the resilient bumper Sit and its movementin the full open position is arrested thereby.

It is desirable that the lower end of the lower fuse tube terminal l9 beclosed off in order to prevent the entrance of extraneous material suchas insects and the like into the interior of the dropout fuse to. Forthis purpose, as shown in FIG. 3-33, a frangible or flexible closuredisc 13b is employed. It is located in an annular groove 131 near thelower end of the lower fuse tube terminal 19 and extends underneaththelower endof the fitting A snap ring 132, also located in the groove131, serves to hold the frangible closure disc 139 in place. When thedropout fuse 16 is operated in a manner such as to cause the flow of areproducts downwardly through the metallic exhaust tube 81 and through thelower fuse tube terminal 19, the frangible or flexible closure disc 136iis readily ruptured or blown out to permit their escape to theatmosphere. Also it can be broken or sprung readily, as describedhereinafter, by an external blow applied to move the operator 116upwardly for triggering the dropout fuse 16.

The details of construction of the external trigger operating mechanism33 are shown in FIGS. 7, 8 and 9 of the drawings to which reference nowwill be had. Here it will be observed that the trip arm 37 is rotatablymounted on a reduced diameter outer end portion of a stud 1% thatextends through the support bracket 34 and is secured thereon by nuts13'] which are threaded on a threa ed portion of the stud 136 as shownin FIG. 8. It will be understood that-the trip arm 37 rotates about thelongitudinal axis of the stud 135, the axis being indicated at 158 inFIGS. 7 and 9. The axis 138 extends in spaced relation to thelongitudinal axis of the fuse tube 17 and transversely thereof when itis in the closed position shown, for example, in FIG. 2. The trip arm 37is biased to its non-operated or retrieved position, shown in FIG. 7, bya helical spring 139 which surrounds the stud 136 having one end ll i-tlanchored to the support bracket 34 and its other end 141 anchored to ahub portion 142 of the trip arm 37. It will be noted in FIG. 9 that thetrip arm 37 has a curved outer end portion the distal end 1 34 of whichis arranged to impact through the frangible closure disc 1%, FIG. 3E,the lower side of the shouL dered fitting 126 on the lower end of theoperator 116 for the purpose of moving it upwardly to effect the releaseof the trigger means 89, FIG. 3-C, in the manner previously described.The closure disc 130 is ruptured by this action.

It is important that the terminal positions of the trip arm 3'7 beaccurately controlled and be adjustable in order to compensate forpossible dislocation of parts of the trigger operating mechanism 33 inrelation to each other and due to varying deflections of the insulatorsl3 and 39. For this purpose an adjustable stop screw 145 is threadedthrough the sleet hood 35, as shown in FIGS. 7 and 9, and it is lockedin place by a lock nut M6. The distal end of the adjustable stop screw145 controls the position to which the trip arm 37 is retrieved or itsnonoperated position as shown in FIG. 7. Another adjustable stop screw147 is provided. It is threaded through one leg of a transverse anglemember M8 that is secured, as by welding, to the underside of the sleethood 35. A look nut M9 serves to hold the stop screw 147 in adjustedposition. As shown in FIG. 9, when a shoulder 37' on the trip arm 37engages the head 147' of the adjustable stop screw 147, further forwardmovement of the trip arm 37 is prevented. The adjustment of the stopscrew 147 is such that the distal end Md of the trip arm 37 is caused tomove the operator 116 upwardly in a positive manner through a distancesufficient to move the cam member 114 to the unlatching position shownin FIG. 3-D of the drawings in order to uulatch positively the triggermeans 89 and release the fusible element terminal 84. The adjustment ofthe stop screw 147 can be such as to permit movement of the operator 116far enough to cause the inner sides 12d-l24 of the openings 113113 inthe cam member 114 to engage wedgingly the flat surfaces l26fl26previously described.

it will be observed that the end of the helical spring 139, which biasesthe trip arm 37 to the non-operated position, extends underneath thetransverse angle member 148, FIGS. 7 and 9, and thereby is held againstmovement with respect to the support bracket 34.

it will be recalled that, when the fusible element terminal 84 isreleased as a result of the impact being applied to the lower end of theoperator 116, the fuse tube 17 is unlatched from the upper line terminal14 and swings downwardly to the open position. It is desirable that thetrip arm 37 be returned to the non-operated position promptly by thespring 139 or at least moved to a position where the curved outer endportion 143 thereof is out of the path of downward swinging movement ofthe dropout fuse 16 so as not to interfere with such action. For thispurpose a trip free connection, shown generally at 150, is provided formechanically interconnecting the trip arm 37 to the actuating lever 33with the arrangement being such that, after the trip arm 37 hascompleted its function of moving the operator 116 upwardly to triggerthe trigger means 89, the operating connection is no longer maintainedand the trip arm 37 is free to be returned to the non-operated positionwithout regard to the position of the actuating lever 38 which may bereturned to the non-operated position at a later time and at arelatively slow speed.

The trip free connection 156 includes a trip free arm 151 having onebifurcated end pivotally secured at 152 to a hub 37" that forms anintegral part of the trip arm 37. As seen in FIGS. 7 and 9, the axis 153of the pivot 152 about which the trip free arm 151 rotates is parallelto the axis 138 about which the trip arm 37 rotates on the stud 136. Itwill be noted that the trip free arm 151 has a shoulder 154 that isarranged to engage a juxtaposed portion of the trip arm 37 for thepurpose of causing conjoint movement thereof when a force is applied tothe trip free arm 151 by the actuating lever 38. The other end 155 ofthe trip free arm 151 is bifurcated and a roller 156 is located betweenthe arms thereof on a pin 157 which extends therethrough and has anextension 158 to which one end of a spring 159 is secured. The spring159 is a coil tension spring and its other end is connected at 160 tothe trip arm 37.

The actuating lever 38 includes an upstanding arm portion 163 that isformed integrally with a base 164 which is secured by bolts 165 to thedistal end of the rotatable insulator 39. The distal end 166 of theupstanding arm portion 163 is rounded and is arranged to engage theroller 156 when the insulator 39 is rotated to rotate the actuatinglever 38. It will be observed that the axis of rotation of the rotatableinsulator 39 is indicated at 167 and that this axis is parallel to theaxis 133 of rotation of the trip arm 37.

When the rotatable insulator 39 is rotated about its axis 167 in acounterclockwise direction as indicated by the arrow 168 in FIG. 7 andthe arrow 169 in FIG. 9, the trip arm 37 is rotated in a clockwisedirection from its position shown in FIG. 7 to the position shown inFIG. 9 and in the direction indicated by the arrow 1170. The arrangementis such that the rounded distal end 166 of the actuating lever 38engages the roller 156 and maintains mechanical engagement therewithuntil the trip arm 37 has rotated sufficiently far to cause the distalend 1% thereof to impact the underside of the disc 136 and thereby thefitting 120 on the lower end of the operator 116 to move it positivelyupwardly a distance sufiicient to trigger the trigger means 89 andpositively release the fusible element terminal 84. Continued rotationof the actuating lever 38 in the direction indicated by the arrow 169causes its rounded end 166 to move past the roller 156 and out of itspath of movement. When this takes place, which is a result of theprovision of the trip free connection 150, the trip arm 37 is no longerdriven in the direction indicated by the arrow 170 and, since thehelical spring 139 has been additionally tensioned by the previousrotation of the trip arm 37 to the operated position, the spring 139 isnot restrained and it biases the trip arm 3'7 to the non-operated orretrieved position shown in FIG. 7.

When the actuating lever 38 subsequently is returned to its non-operatedposition by rotation of its insulator 39 in a clockwise direction, therounded end 166 engages the roller 156. However, since the trip arm 37is prevented sass? from any further rotation in a counterclockwisedirection by the adjustable stop screw I145, the engagement of theroller 156 by the rounded end 166 swings the trip free arm 151 about itspivot 152 and tensions the spring 159. Then, after the rounded end 166has moves to the position shown in FIG. 7 and out of mechanicalengagement with the roller 156, the spring 159 retrieves the trip freearm 151 and rotates it in a clockwise direction until its shoulder i54-engages the trip arm 37 in the position shown in FIG. 7.

What is claimed as new is:

1. Apparatus for triggering a dropout fuse including a fuse tube latchedat its upper end to an upper line terminal and pivoted at its lower endto a lower line terminal, a fusible element controlling the latch atsaid upper end and adapted on blowing to draw an arc and discharge theare products through said lower end, trigger means to release saidfusible element in its unblown state to unlatch said latch, and arod-like operator movable endwise through said lower end upwardly intosaid fuse tube to trigger said trigger means for releasing said fusibleelement to interrupt the circuit and to unlatch the latch means at itsupper end and permit it to swing downwardly to open position comprising,in combination:

(a) a support bracket extending laterally from said lower line terminal,

(11) trip arm means rotatably mounted at one end on said support bracketwith its distal end normally out of the path of the are products thatflow from said lower end of said fuse tube on blowing of said fusibleelement and arranged to swing about an axis spaced from and extendingtransversely of the longitudinal axis of said dropout fuse and parallelto the plane of swinging movement of said fuse tube for engaging at itsdistal end said rod-like operator and moving it endwise upwardly intosaid fuse tube, and

(c) means for rotating said trip arm to engage said operator.

2. The invention, as set forth in claim 1, wherein a sleet hood ismounted on the support bracket in overlying relation to the trip arm inits non-operated position and in spaced relation to the lower lineterminal.

3. The invention, as set forth in claim 1, wherein:

(a) a trip arm spring reacts between the support bracket and the triparm to bias said trip arm to its non-operated position, and

(b) a trip free connection is provided between said trip arm and themeans for rotating it to engage the operator.

4. The invention, as set forth in claim 3, wherein adjustable stops aremounted on the support bracket and cooperate with the trip arm to limitthe extent of its rotation in either direction.

5. The invention, as set forth in claim 3, wherein:

(a) the means for rotating the trip arm includes an actuating lever, and

(b) rotatable insulating means supports said actuating lever forrotation about an axis parallel to the axis of rotation of the trip arm.

6. The invention, as set forth in claim 5, wherein the trip freeconnection includes:

(a) a trip free arm pivoted at one end to the trip arm about an axisparallel to its axis of rotation, and

(b) a trip free arm spring biases said trip free arm into engagementwith said trip arm,

(0) the distal end of the actuating lever when rotated in a fusetriggering direction engages the distal end of said trip free arm torotate said trip arm, tension the trip arm spring, cause the distal endof said trip arm to engage the rod-like operator, interrupt the circuitand to unlatch the dropout fuse, and finally disengage said trip freearrn whereupon said trip arm is retrieved by said trip arm spring to itsnon-operated position,

(d) the distal end of said actuating lever when rotated in the oppositedirection engages said distal end of 13 said trip free arm, rotates itaway from said trip arm, tensions said trip free arm spring, anddisengages said distal end of said trip free arm.

7. The invention, as set forth in claim 1, wherein:

(a) insulators extending laterally from a support carry the upper andlower line terminals at their distal ends, and

(b) an insulator rotatably mounted at one end on said support parallelto and adjacent to the insulator that carries the lower line terminalcarries an actuating lever at its distal end for rotating the trip arm.

8. The invention, as set forth in claim 7, wherein:

(a) a plurality of actuating levers are mounted on a plurality ofrotatable insulators for triggering a plurality of dropout fuses, and

(b) means are operatively connected to said rotatable l4 insulators forrotating them to trigger simultaneously said dropout fuses. 9. Theinvention, as set forth in claim 8, wherein an operator is mechanicallyconnected to the rotatable in- 5 sulators to cause the respectiveactuating levers to impact the respective operators in the dropoutfuses.

References Cited by the Examiner UNITED STATES PATENTS 2,344,113 3/44Schultz 200-l49 X 2,849,578 8/58 Hart 200-146 2,889,434 6/59 Lingal200-146 X 2,963,560 12/60 Koerner et al 200-48 15 BERNARD A. GILHEANY,Primary Examiner.

ROBERT K. SCHAEFER, Examiner.

1. APPARATUS FOR TRIGGERING A DRIPOUT FUSE INCLUDING A FUSE TUBE LATCHEDAT ITS UPPER END TO AN UPPER LINE TERMINAL AND PIVOTED AT ITS LOWER ENDTO A LOWER LINE TERMINAL, A FUSIBLE ELEMENT CONTROLLING THE LATCH ATSAID UPPER END AND ADAPTED ON BLOWING TO DRAW AN ARC AND DISCHARGE THEARC PRODUCTS THROUGH SAID LOWER END, TRIGGER MEANS TO RELEASE SAIDFUSIBLE ELEMENT IN ITS UNBLOWN STATE TO UNLATCH SAID LATCH, AND AROD-LIKE OPERATOR MOVABLE ENDWISE THROUGH SAID LOWER END UPWARDLY INTOSAID FUSE TUBE TO TRIGGER SAID TRIGGER MEANS FOR RELEASING SAID FUSIBLEELEMENT TO INTERRUPT THE CIRCUIT AND TO UNLATCH THE LATCH MEANS AT ITSUPPER END AND PERMIT IT TO SWING DOWNWARDLY TO OPEN POSITION COMPRISING,IN COMBINATION: (A) A SUPPORT BRACKET EXTENDING LATERALLY FROM SAIDLOWER LINE TERMINAL, (B) TRIP ARM MEANS ROTATABLY MOUNTED AT ONE END ONSAID SUPPORT BRACKET WITH ITS DISTAL END NORMALLY OUT OF THE PATH OF THEARC PRODUCTS THAT FLOW FROM SAID LOWER END OF SAID FUSE TUBE ON BLOWINGOF SAID FUSIBLE ELEMENT AND ARRANGED TO SWING ABOUT AN AXIS SPACED FROMAND EXTENDING TRANSVERSELY OF THE LONGITUDINAL AXIS OF SAID DROPOUT FUSEAND PARALLEL TO THE PLANE OF SWINGING MOVEMENT OF SAID FUSE TUBE FORENGAGING AT ITS DISTAL END SAID ROD-LIKE OPERATOR AND MOVING IT ENDWISEUPWARDLY INTO SAID FUSE TUBE, AND (C) MEANS FOR ROTATING SAID TRIP ARMTO ENGAGE SAID OPERATOR.